Snap muzzle graphics rotation for invisible weapons

Invisible weapons don't need rotation interpolation. Just snap rotation directly so the muzzle graphic on bunkers appears where it should the first time.

src/display3d.cpp

@@ -2774,6 +2774,7 @@ static void renderStructureTurrets(STRUCTURE *psStructure, iIMDShape *strImd, PI
 				// draw Weapon/ECM/Sensor for structure
 				if (flashImd[i] != nullptr)
 				{
+					rot = psStructure->asWeaps[i].rot; // Snap rotation so the muzzle graphic appears where it should, see aiUpdateStructure().
 					iIMDShape *pFlashDisplayIMD = flashImd[i]->displayModel();
 					glm::mat4 matrix(1.f);
 					// horrendous hack